1. Field of the invention:
The present invention relates to a display unit having a tilt mechanism for varying the angle of a display screen with respect to the vertical direction.
2. Description of the Prior Art:
FIG. 2 of the accompanying drawings illustrates a tilt mechanism in a conventional display unit. The display unit has a body 1 including a lower support 2 having a partly cylindrical or arcuate outer surface of a radius of curvature r.sub.1 and angularly movable about a central point O.sub.1. The support 2 is swingably supported by projections 4 on a base 3. When the angle of a display screen 5 of the display unit is to be varied with respect to the vertical direction, a front outer casing of the display unit is vertically moved to cause the arcuate surface of the support 2 to slide on the projections 4. At this time, the display screen 5 is moved an interval a.sub.1 in the back-and-forth direction while following the path through points P.sub.1, P.sub.2,P.sub.3.
With the conventional display unit, however, the display screen is moved back and forth to a large extent each time its angle is varied. When the angle of the display screen is changed, therefore, the distance of the visual point of the user and the display screen is also changed to thereby cause the display screen to be seen differently by the user. This requires the user to change the attitude or move the chair or desk so that the user can see the display screen clearly and comfortably. The user is, however, subjected to an extra burden and increased fatigue in changing the attitude or moving the chair or desk. If the user does not take any action to improve visibility, then the user has to see a display screen which is visually different from the previous display screen. It takes a long time for the user to become accustomed to such a visually different display screen, or the user tends to fatigue because of reduced comfort which the user has in seeing the display screen.
For reducing the movement of the display screen 5 in the back-and-forth direction, it would be possible to employ a support 6, shown by the dotted line, having an arcuate surface of a radius r.sub.1 ' of curvature and angularly movable about a central point 0.sub.1 ', the radius r.sub.1 ' being longer than radius r.sub.1. However, the user would be required to move the support 6 for a greater interval on the projections 4 because of the larger radius when the angle of the display screen 5 is adjusted. Another problem with the proposed solution is that the curvature of the arcuate surface of the support 6 would be reduced due to the reduced radius, resulting in difficulty in turning the support 6.
U.S. Pat. No. 4,068,961 issued on Jan. 17, 1978 discloses a swivel joint which allows an object to be provided with limited and controlled movement in two orthogonal directions.